Infusion pump devices and systems are relatively well known in the medical arts, for use in delivering or dispensing an agent, such as insulin or another prescribed medication, to a patient. A typical infusion pump includes a pump drive system which typically includes a small motor and drive train components that convert rotational motor motion to a translational displacement of a plunger (or stopper) in a reservoir that delivers medication from the reservoir to the body of a user via a fluid path created between the reservoir and the body of a user. Use of infusion pump therapy has been increasing, especially for delivering insulin for diabetics.
Continuous insulin infusion provides greater control of a patient with diabetes glucose levels, and hence, control schemes are being developed that allow insulin infusion pumps to monitor and regulate a user's blood glucose level in a substantially continuous and autonomous manner. Regulating blood glucose level is complicated by variations in the response time for the type of insulin being used along with variations in a user's individual insulin response and daily activities (e.g., exercise, carbohydrate consumption, bolus administration, and the like). Additionally, the responsiveness of the glycemic control can be influenced by delay associated with feedback regarding the user's current glucose level.
For example, some continuous glucose monitoring (CGM) sensors measure the glucose in the interstitial fluid (ISF) while blood glucose meters used for calibration measure the blood glucose in the capillaries. Blood glucose diffuses from the capillary to the interstitial space where it is measured by the CGM sensor, which results in ISF glucose measurements lagging behind the blood glucose measurements based on the time it takes glucose to diffuse from the capillary to the interstitial space. In addition to the physiological time lag, signal processing (e.g., filtering), signal interference (e.g., noise), and sensor characteristics may also influence the amount by which the ISF glucose measurements lag the blood glucose in the capillaries. Accordingly, there is a need to mitigate the effects of sensor lag and improve the responsiveness and efficacy of glycemic control.